A vehicular transmission provided with a device for locking rotation in one direction which prohibits reverse rotation of an engine while allowing normal rotation of the engine by being disengaged when an engine output shaft normally rotates and engaged when the engine output shaft is about to reversely rotate is conventionally known.
A vehicular transmission of Patent Literature 1 is provided with a one-way clutch as a locking device and a planetary gear mechanism provided with rotational elements to each of which an output shaft of the one-way clutch and a transmission output shaft side (drive wheel side) are connected. A hybrid system including the vehicular transmission is provided with a first motor-generator connected to another rotational element of the planetary gear mechanism and a second motor-generator connected to the transmission output shaft side (drive wheel side). In the vehicular transmission of Patent Literature 1, the one-way clutch is arranged between an engine and the planetary gear mechanism in an axial direction of a transmission input shaft. In the hybrid system of Patent Literature 1, the first and second motor-generators are used together as power sources at the time of travel.
A vehicular transmission of Patent Literature 2 is provided with a one-way clutch as a locking device, a damper device which inhibits torque variation between a transmission input shaft and an engine output shaft, and a planetary gear mechanism provided with rotational elements to each of which the transmission input shaft and a transmission output shaft side (drive wheel side) are connected. A hybrid system including the vehicular transmission is provided with a first motor-generator connected to another rotational element of the planetary gear mechanism and a second motor-generator connected to the transmission output shaft side (drive wheel side). In the vehicular transmission of Patent Literature 2, the one-way clutch is arranged between the planetary gear mechanism and the first motor-generator in an axial direction of the transmission input shaft and an inner ring of the one-way clutch is connected to the rotational element (rotational element to which the first motor-generator is connected) of the planetary gear mechanism.
Patent Literature 3 discloses a vehicular transmission to which a meshing clutch is applied as a locking device. The meshing clutch may allow normal rotation of an engine in a disengaged state and prohibit reverse rotation of the engine by stopping rotation of an engine rotational shaft in an engaged state. In a hybrid system including the vehicular transmission, the meshing clutch is engaged at the time of EV travel and regenerative travel and the meshing clutch is disengaged at the time of engine travel.